Shell for lamp sockets



' March A. D COWPERTHWAlT ET AL 1,350,535

SHELL FOR LAMP SOCKETS Filed Sept. 21, 1928 Patented Mar. 22, 1932 UNITED STATES SHELL FOR LAMP SOCKETS Application filed September 21, 1928. Serial No. 307,357.

This invention relates to improvements in sockets for electric lamps and particularly to socket shells for such sockets.

It is an object of the invention to provide a socket shell which while having reliable resilient contact means for making detachable electric connections to the lamp will be simple, easily made and capable of being produced by machinery at a low cost of manufacture.

With this general object in view, the invention consists in the features, combinations, details of construction and arrangements of parts which will be described in connection with the accompanying drawings and then more particularly pointed out in the claim.

In the drawings:

Fig. l is a plan view of a socket shell;

Fig. 2 is an elevation showing a lamp in place in a socket, the socket comprising a socket shell embodying the invention, said shell being shown in elevation;

Fig. 3 is an elevation partly in section of a shell removed from a socket, with a lamp in place in said shell, the lamp being partly broken away, and

Fig. 4 is a side elevation of a spring ring such as that used in the construction shown in Fig. 3.

Referring to the drawings, A is a socket shell formed of sheet metal, such for example as brass, and having the usual screw threads 1 of rounded crosssection for engagement with the socket husk E, and with the lamp base in the usual way.

The outer end of the shell A may have any desired contour but most advantageously has an outwardly flared skirt as indicated at 2.

The inner end of the socket shell A is formed tubular to provide a chamber in which there is placed a movable diaphragm B of insulating material, this diaphragm advantageously being relatively thick so that it may slide within the chamber without tending to cant as it might if too thin. The center of the diaphragm B is provided with a suitable contact device arranged to make contact with the central terminal of an electric lamp, as for example, the central terminal, indicated at 3 of the lamp C. In what is now I phragm then inserted. To hold considered the best embodiment of the invention the contact device is a tubular sheet metal rivet, indicated at 4, which is inserted in a hole in the diaphragm B and riveted in place by flanging its end edge out-ward. This contact device has the flanged head of the tubular rivet arranged to come into contact with the central lamp terminal 3, thereby providing a relatively wide and flat contact, thus serving to insure a good contact with the lamp terminal even if the latter is somewhat out of the center of the lamp base.

The extreme inner end of the shell A is flanged inward, as indicated at 5 and between this flange and the diaphragm there is inserted a suitable spring ring D which is specially constructed as an annulus of resilient sheet metal, the annulus being pressed or bent into a series of convolutions as shown for example in Fig. 4 so as to give three points of bearing against the diaphragm B and also three other points of contact against the flange 5 of the shell, the points of contact at one side of the ring D being intermediate the points of contact on the other side of the ring. In the best embodiment of the inven tion the bearing points of the spring ring on the diaphragm are substantially 120 degrees apart, which tends to give a uniformly distributed spring pressure on the diaphragm and thereby largely reduces if not entirely eliminates any danger of canting the diaphragm which would cause it to lock or stick against the inner walls of the chamber in which it is located.

In assembling the parts the central tubular rivet 4c is riveted to the diaphragm, the spring D is pushed into place and the dia the latter in place and to restrict its movement, suitable stop devices are provided. In the simplest form these are protuberances stamped or punched inward from the shell, these being indicated at 6.

In using the shell in the manufacture of sockets, the socket husk, which is usually of pressed or cast insulating material and generally of the form indicated at E, Fig. 2, is threaded onto the two electric conductors indicated at F, Fig. 2, leaving the said conwhere it 'is secured by solder.

inner face of the solder may readily be dropped into the hollow I shell.

F tral terminal of threaded portion of the lamp base its central rivet, are supplied to the rivet to secure the strands in place. The end I of the other conductor is soldered to the outer 7 surface of the shell.

The socket may then be slid down the conductors and forced onto the It is clear that when an electric lamp C isscrewed into the socket shell the outer terminal of the base will make contact with the socket shell while the central terminal of the lamp, indicated at 3, will contact with the head of'the rivet 4, whereby, upon screwing the lamp in' further, the diaphragm will yield and move back in its chamber, compressing the spring ring D, the spring pressure increasing as the lamp is screwed further into the shell thereby lnsuring a strong pressure between the head of the rivet and the central terminal of the lamp.

This spring pressure is sufficient to maintain a good contact not only between the centhe socket shell and'that of the lamp, but to take up any lost motion in the screw threads and thereby maintain a good contact between the socket shell and the which forms its outer termina 1 V One of the important features of the invention is that the spring device D cannot cause a short circuit by simultaneously contacting with both terminals of the circuit, and is suffi- 'ciently spaced fromone terminal or the other that sparking across from the spring device to either terminal is not possible. For example, in the construct1on shown in the drawings, the sprlng ring D hes close to and makes an electricalcontact with the flanged end 5 of the shell A, but as it is an annulus it is at all'points far removed from the central terminal or rivet 4 and from the conductor connected to it, this conductor, of course, being insulated excepting the bared end which is downinside the tubular rivet a. I

' By the-construction shown and described,

the cost of production is greatly reduced, be-

cause the parts can be assembled by automatic machines of the types now in common use.

For example, the washers B of insulating material and the tubular rivets 4 are supplied to the hoppers or receptacles of automatic machines, which properly assemble the rivet and washer and then rivet, or turn outward, the flange at the open end of the rivet, so as to secure the rivet inplace firmly.

The socket shells A, the spring washers D, and the insulating washers B, each carrying hoppers rotatable in assembled of automatic machines which feed the parts, one set at a time, to the assembling mechanism. Where the socket shell is held with its outer end upward, the spring washer D is fed into the shell, then an insulating washer B is pushed into the shell on top of the spring washer, and while the insulating washer is pressed down. slightly against the spring washer, the protuberances 6 are pressed or punchedinward to hold the parts in their assembled positions. Owing to the use of an annular spring washer, there is practically no danger of the washer clogging the feed chute or hopper of an automatic machine. Hence, the feeding of the parts proceeds with certainty.

It will be seen that the socket shell A with the husks E are made and the socket shell assembled with it and the'conductors. Usually the socket shells are made at one factory and the finished socket made at another factory. By the construction of socketshell with its contained parts as heretofore described, the labor of completing the socket, which heretofore has been materially reduced.

What we claim is: A metallic socket comprising a threaded portion arranged to receive the threaded base of an incandescent lamp, an end portion forming a tubularcham her and terminating in an inwardly extending annular flange, a movable cylindrical diaphragm of insulating material located in said chamber, a central terminal secured at the center of the diaphragm, a spring within the socket shell arranged to press the diaphragm at a plurality of points and said flange at a: to urge the central 7 plurality of points and terminal toward an incandescentlamp, said spring being prevented by said shell from contacting with said central terminal, said shell, spring and diaphragm being relatively position, and means formed integrally with the socket shell for limiting forward movement of the diaphragm in the chamber.

ARTHUR D. COWPERTHWAIT.

FREDERICK REUTTEB.

largely hand labor, is

shell for lamp-sockets; 

